Wireless method for monitoring and controlling food temperature

ABSTRACT

A method for controlling refrigeration including a simulated product temperature sensor operable to measure a simulated product temperature from a refrigeration case and a transceiver in communication with said simulated product temperature sensor and operable to wirelessly transmit data. A receiver receives the wirelessly transmitted data and a controller in communication with the receiver controls the refrigeration system based upon the wirelessly transmitted data from the refrigeration case.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/702,993, now U.S. Pat. No. 6,378,315 filed on Oct. 31, 2000, which isa continuation-in-part of U.S. patent application Ser. No. 09/564,173filed on May 3, 2000, now U.S. Pat. No. 6,502,409. The disclosures ofthe above applications are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to monitoring and controllingtemperature and, more specifically, a method and apparatus formonitoring and controlling food temperature.

BACKGROUND OF THE INVENTION

Produced food travels from processing plants to grocery stores, wherethe food product remains on display case shelves for extended periods oftime. For improved food quality, the food product should not exceedcritical temperature limits while being displayed in the grocery storedisplay cases. For uncooked food products, the product temperatureshould not exceed 41° F. For cooked food products, the producttemperature should not be less than 140° F. In other words, the criticaltemperature limits are approximately 41° and 140° F. Between thesecritical temperature limits, bacteria grow at a faster rate.

One attempt to maintain food product temperature within safe limits isto monitor the discharge air temperature to ensure that the display casedoes not become too warm or too cold. But the food product temperatureand discharge air temperature do not necessarily correlate; that is,discharge air temperature and food product temperature will notnecessarily have the same temperature trend because food producttemperatures can vary significantly from discharge air temperature dueto the thermal mass of the food product. Further, during initial startupand display case defrost, the air temperature can be as high as 70° F.while food product temperature is much lower for this typically shortinterval. Finally, it is impractical to measure the temperature of foodproducts at regular intervals in order to monitor food producttemperature in a display case.

More specifically, in a conventional refrigeration system, a maincontroller typically logs or controls temperature. Conventionally, themain controller is installed in the compressor room, which is located onthe roof or back of the grocery store. The conventional method formonitoring and controlling the display case temperature requires adischarge air temperature sensor mounted in the display case. Thedischarge air temperature sensor is typically connected to an analoginput board, which is also typically located in the compressor room. Atemperature wire must be pulled from the display case to the compressorroom, which is typically difficult and increasingly expensive dependingon how far away the compressor room is from the display case. Further,this wiring and installation process is more expensive and extremelycumbersome when retrofitting a store.

SUMMARY OF THE INVENTION

An apparatus, system, and method for controlling a refrigeration systemaccording to the invention overcomes the limitations of the prior art byproviding wireless transmission of simulated product temperature data.An apparatus according to the invention includes a plurality of circuitshaving at least one refrigeration case and a compressor rack. Anelectronic evaporator pressure regulator in communication with eachcircuit controls the temperature of one of the circuits. A sensor incommunication with each circuit measures a parameter from the circuit,and a transceiver in communication with the sensor wirelessly transmitsthe measured parameter. A receiver receives the wirelessly transmittedmeasured parameter. A controller in communication with the receivercontrols each electronic evaporator pressure regulator and a suctionpressure of said compressor rack based upon the wirelessly transmittedmeasured parameter from each of the circuits.

Preferably, at least one of the sensors in communication with each ofthe circuits is a product-simulating probe operable to simulate aproduct temperature. The probe for simulating product temperatureincludes a housing containing a thermal mass having thermo-physicalproperties similar to food product, and a temperature sensing elementfor measuring the temperature of the thermal mass. Preferably, thethermal mass is contained within a plastic bag within the housing. Thetransceiver, which is connected to the temperature-sensing element,wirelessly transmits the measured temperature data to the receiver. Thetransceiver may be disposed within the housing, or positioned externalto the housing. The housing preferably includes a middle platesupporting the thermal mass in a first portion of the housing andcontaining the temperature sensing element in a second portion of saidhousing. Most preferably, the middle plate includes a channelcommunicating with the second portion and extending into the firstportion, and the temperature-sensing element is positioned within thechannel such that the thermal mass substantially surrounds the channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a refrigeration system employing a methodand apparatus for refrigeration system control according to theteachings of the preferred embodiment in the present invention;

FIG. 2 is a perspective view of a product-simulating probe according tothe invention;

FIG. 3 is a perspective view of the bottom of the product-simulatingprobe of FIG. 2;

FIG. 4 is an exploded view of the product-simulating probe of FIGS. 2and 3;

FIG. 5 is a block diagram illustrating one configuration fortransferring product temperature data from a display case to a maincontroller according to the invention;

FIG. 6 is a block diagram of another configuration for transferringproduct temperature data from a display case to a main controlleraccording to the invention;

FIG. 7 is a block diagram illustrating yet another configuration fortransferring product temperature data and other monitored data from adisplay case to a main controller according to the invention;

FIG. 8 is a flow chart illustrating circuit temperature control using anelectronic pressure regulator; and

FIG. 9 is a flow chart illustrating floating circuit or case temperaturecontrol based upon a product simulator temperature probe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a detailed block diagram of a refrigeration system10 according to the teachings of the preferred embodiment in the presentinvention is shown. The refrigeration system 10 includes a plurality ofcompressors 12 piped together in a compressor room 6 with a commonsuction manifold 14 and a discharge header 16 all positioned within acompressor rack 18. The compressor rack 18 compresses refrigerant vaporthat is delivered to a condenser 20 where the refrigerant vapor isliquefied at high pressure. This high-pressure liquid refrigerant isdelivered to a plurality of refrigeration cases 22 in a grocery storefloor space 8 by way of piping 24. Each refrigeration case 22 isarranged in separate circuits 26 consisting of a plurality ofrefrigeration cases 22 that operate within a similar temperature range.FIG. 1 illustrates four (4) circuits 26 labeled circuit A, circuit B,circuit C and circuit D. Each circuit 26 is shown consisting of four (4)refrigeration cases 22. Those skilled in the art, however, willrecognize that any number of circuits 26 within a refrigeration system10, as well as any number of refrigeration cases 22 may be employedwithin a circuit 26. As indicated, each circuit 26 will generallyoperate within a certain temperature range. For example, circuit A maybe for frozen food, circuit B may be for dairy, circuit C may be formeat, etc.

Because the temperature requirement is different for each circuit 26,each circuit 26 includes a pressure regulator 28, preferably anelectronic stepper regulator (ESR) or valve, that acts to control theevaporator pressure and hence, the temperature of the refrigerated spacein the refrigeration cases 22. Preferably, each refrigeration case 22also includes its own evaporator and its own expansion valve (notshown), which may be either a mechanical or an electronic valve forcontrolling the superheat of the refrigerant. In this regard,refrigerant is delivered by piping 24 to the evaporator in eachrefrigeration case 22. The refrigerant passes through the expansionvalve where a pressure drop occurs to change the high-pressure liquidrefrigerant to a lower-pressure combination of liquid and vapor. As thewarmer air from the refrigeration case 22 moves across the evaporatorcoil, the low-pressure liquid turns into a gas. This low-pressure gas isdelivered to the pressure regulator 28 associated with that particularcircuit 26. At the pressure regulator 28, the pressure is dropped as thegas returns to the compressor rack 18 through the common suctionmanifold 14. At the compressor rack 18, the low-pressure gas is againcompressed to a higher pressure and delivered to the condenser 20, whichagain creates a high-pressure liquid to start the refrigeration cycleover.

To control the various functions of the refrigeration system 10, a mainrefrigeration controller 30 is used and configured or programmed toexecutes a control algorithm and includes configuration and loggingcapabilities. The refrigeration controller 30 controls the operation ofeach pressure regulator (ESR) 28, as well as the suction pressure setpoint for the entire compressor rack 18. The refrigeration controller 30is preferably an Einstein Area Controller offered by CPC, Inc. ofAtlanta, Ga., or any other type of programmable controller that may beprogrammed, as discussed herein and as discussed more fully is U.S.patent application Ser. No. 09/539,563, filed Mar. 31, 2000, entitled“Method And Apparatus For Refrigeration System Control Using ElectronicEvaporator Pressure Regulators,” incorporated herein by reference. Therefrigeration controller 30 controls the bank of compressors 12 in thecompressor rack 18 through an input/output module 32. The input/outputmodule 32 has relay switches to turn the compressors 12 on and off toprovide the desired suction pressure. A separate case controller, suchas a CC-100 case controller, also offered by CPC, Inc. of Atlanta, Ga.may be used to control the superheat of the refrigerant to eachrefrigeration case 22 through an electronic expansion valve in eachrefrigeration case 22 by way of a communication network or bus, asdiscussed more fully the aforementioned U.S. patent application Ser. No.09/539,563, filed Mar. 31, 2000, entitled “Method And Apparatus ForRefrigeration System Control Using Electronic Evaporator PressureRegulators.” Alternatively, a mechanical expansion valve may be used inplace of the separate case controller. Should separate case controllersbe utilized, the main refrigeration controller 30 may be used toconfigure each separate case controller, also via the communication bus.

In order to monitor the suction pressure for the compressor rack 18, apressure transducer 40 is preferably positioned at the input of thecompressor rack 18 or just past the pressure regulators 28. The pressuretransducer 40 delivers an analog signal to an analog input board 38,which measures the analog signal and delivers this information to themain refrigeration controller 30, via the communication bus 34. Theanalog input board 38 may be a conventional analog input board utilizedin the refrigeration control environment. The pressure transducer 40enables adaptive control of the suction pressure for the compressor rack18, further discussed herein and as discussed more fully in theaforementioned U.S. patent application Ser. No. 09/539,563, filed Mar.31, 2000, entitled “Method And Apparatus For Refrigeration SystemControl Using Electronic Evaporator Pressure Regulators.”

To vary the openings in each pressure regulator 28, an electronicstepper regulator (ESR) board 42 drives up to eight (8) electronicstepper regulators 28. The ESR board 42 is preferably an ESR-8 boardoffered by CPC, Inc. of Atlanta, Ga., which consists of eight (8)drivers capable of driving the stepper valves 28, via control from themain refrigeration controller 30. The main refrigeration controller 30,input/output module 32, and ESR board 42 are located in a compressorroom 6 and are preferably daisy chained via the communication bus 34 tofacilitate the exchange of data between them. The communication bus 34is preferably either an RS-485 communication bus or a LonWorks Echelonbus.

The suction pressure at the compressor rack 18 is dependent in thetemperature requirement for each circuit 26. For example, assume circuitA operates at 10° F., circuit B operates at 15° F., circuit C operatesat 20° F. and circuit D operates at 25° F. The suction pressure at thecompressor rack 18, which is sensed through the pressure transducer 40,requires a suction pressure set point based on the lowest temperaturerequirement for all the circuits 26, which, for this example, is circuitA, or the lead circuit. Therefore, the suction pressure at thecompressor rack 18 is set to achieve a 10° F. operating temperature forcircuit A. This requires the pressure regulator 28 to be substantiallyopened 100% in circuit A. Thus, if the suction pressure is set forachieving 10° F. at circuit A and no pressure regulator valves 28 wereused for each circuit 26, each circuit 26 would operate at the sametemperature. Because each circuit 26 is operating at a differenttemperature, however, the electronic stepper regulators or valves 28 areclosed a certain percentage for each circuit 26 to control thecorresponding temperature for that particular circuit 26. To raise thetemperature to 15° F. for circuit B, the stepper regulator valve 28 incircuit B is closed slightly, the valve 28 in circuit C is closedfurther, and the valve 28 in circuit D is closed even further providingfor the various required temperatures.

Each electronic pressure regulator (ESR) 28 is preferably controlled bythe main controller 30 based on food product temperatures approximatedby a product simulating probe 50, or based on multiple temperaturereadings including air-discharge temperature sensed by a dischargetemperature sensor 48 and/or food product temperatures approximated by aproduct simulating probe 50 and transmitted through a display module 46.

In order to control the opening of each pressure regulator 28 based onthe temperature of the food product inside each refrigeration case 22,the product temperature is approximated using the product-simulatingprobe 50 according to the invention. In this regard, each refrigerationcase 22 is shown having a product-simulating probe 50 associatedtherewith. Each refrigeration case 22 may have a separateproduct-simulating probe 50 to take average/minimum/maximum temperaturesused to control the pressure regulator 28 or a single product-simulatingprobe 50 may be used for a given circuit 26 of refrigeration cases 22,especially because each refrigeration case 22 in operates withinsubstantially the same temperature range for a given circuit 26. Thesetemperature inputs are wirelessly transmitted to an analog inputreceiver 94, which returns the information to the main refrigerationcontroller 30 via a communication bus 96.

The product-simulating probe 50, as shown in FIGS. 2–4, providestemperature data to the main controller 30. Preferably, the productsimulating probe 50 is an integrated temperature measuring andtransmitting device including a box-like housing 70 encapsulating athermal mass 74 and a temperature sensing element 80 and including awireless transceiver 82. The housing 70 includes a cover 72 secured to abase 86, and magnets 84 mounted to the cover 72 facilitate easyattachment of the probe 50 to the display case 22. Preferably, the cover72 is adhered to the base 86 to seal the thermal mass 74 therein. Inplace of magnets 84, a bracket 85 may be used by securing the bracket 85to the display case 22 and attaching the probe 50 by sliding the bracketinto a complimentary slot 87 on the base 86 of the probe 50.

The thermal mass 74 is a container housing a material havingthermo-physical characteristics similar to food product. Because foodproduct predominantly contains water, the thermo-physical simulatingmaterial is preferably either salt water or a solid material that hasthe same thermal characteristics as water, such as low-densitypolyethylene (LDPE) or propylene glycol. The container for the thermalmass is preferably a plastic bag, and most preferably a pliablepolypropylene bag, sealably containing the simulating material.Alternatively, a more rigid material can be used, but should include acentrally disposed channel 77 for accommodating the temperature sensingelement 80 in close proximity to the material having thermo-physicalcharacteristics similar to food product. Preferably, the thermal mass 74is a 16-ounce (1-pint) sealed-plastic container filled with four percent(4%) salt water.

The temperature-sensing element 80 is embedded in the center of thethermal mass 74 so that the temperature product probe 50 measures thesimulated internal temperature of food products. The temperature-sensingelement 80 is preferably a thermistor. A middle plate 78 seals thetemperature sensing element 80 and transceiver 82 relative the thermalmass 74 and includes a transversely extending tube 76 that supports thetemperature sensing element 80 within the channel 77 of the thermal mass74. When a pliable plastic material is used to contain the materialhaving thermo-physical characteristics similar to food product, thepliable plastic material forms the channel 77 by accommodating the tube76 within the thermal mass 74. A gasket 89 is disposed between themiddle plate 78 and the base 86 to seal the space between the middleplate 78 and the bottom of the base 86 containing the transceiver 82.Fasteners 91 received through the base 86 secure the middle plate 78 tothe base 86 through threaded reception in nut inserts 93 in-molded orsecured to the middle plate 78.

The wireless transceiver 82 preferably includes a signal-conditioningcircuit, is mounted between the base 86 and the middle plate 82, and isconnected to the temperature sensing element 80 via a wire 88. Thewireless transceiver 82 is preferably a radio frequency (RF) device thattransmits and receives parametric data and control inputs and outputs.Preferably, the wireless transceiver 82 is a standalone transceiverand/or transmitter that can be positioned independently of otherhardware, such as repeaters, operating on internal or external power,that retransmit at the same or different radio frequencies as theparametric data and control inputs and outputs, and one or moretransceivers 82 or receivers 94 that are linked to the main controller30. The wireless transceiver 82 preferably operates on an internal powersource, such as a battery, but can alternatively by powered by anexternal power source.

Preferably, as shown in FIG. 5, the product simulating probe 50 monitorsthe performance of the display case 22. Preferably, one probe 50 isplaced within each display case 22. The product-simulating probe 50wirelessly transmits simulated product temperature data to the receiver94, which collects the temperature data and retransmits it to the maincontroller 30 via the communication bus 96. The main controller 30 logsand analyzes the temperature data, and controls the temperature of thedisplay cases 22 based on the monitored temperature data.

As shown in FIG. 6, an alternative embodiment of the invention includesdisposing a transceiver 82′ apart from a product simulating probe 50′and then connecting the transceiver 82′ to the probe 50′ via a wire 84.For this variation of the invention, the product simulating probe 50′does not include an internal transceiver 82, but is connected to anexternal transceiver 82′ connected to the temperature sensing element 80via the wire 84. Optionally, as shown, a discharge air temperaturesensor 48, or any other sensor, can similarly be connected to thetransceiver 82′ for transmission of measured data. The wirelesstransceiver 82′ is mounted externally on the display case 22; forexample, mounted on the top of the display case 22. The method oftransmitting the temperature data from the product simulating probe 50′to the main controller 30 remains the same as described above.

As opposed to using an individual product simulating probe 50 or probe50′ with an external transceiver 82′ to transmit the temperature for arefrigeration case 22 to the receiver 94, a temperature display module46 may alternatively be used as shown in FIG. 7. The temperature displaymodule 46 is preferably a TD3 Case Temperature Display, also offered byCPC, Inc. of Atlanta, Ga. The display module 46 is preferably mounted ineach refrigeration case 22, and is connected to a wireless transceiver82′. Each module 46 preferably measures up to three (3) temperaturesignals, but more or fewer can be measured depending on the need. Thesemeasured signals include the case discharge air temperature measured bya discharge temperature sensor 48, the simulated product temperaturemeasured by a product simulator temperature probe 50′, and a defrosttermination temperature measured by a defrost termination sensor 52.These sensors may also be interchanged with other sensors, such asreturn air sensor, evaporator temperature or clean switch sensor. Thedisplay module 46 also includes an LED display 54 that can be configuredto display any of the temperatures and/or case status(defrost/refrigeration/alarm).

The display module 46 will measure the case discharge air temperature,via the discharge temperature sensor 48 and the product simulatedtemperature, via the product probe temperature sensor 50 and thenwirelessly transmit this data to the main refrigeration controller 30via the wireless transceiver 82′, which transmits data to the receiver94 connected to the main controller 30 via the communication bus 96.This information is logged and used for subsequent system controlutilizing the novel methods discussed herein.

Further, the main controller 30 can be configured by the user to setalarm limits for each case 22, as well as defrosting parameters, basedon temperature data measured by the probe 50, or discharge temperaturesensor 48, or any other sensor including the defrost termination sensor52, return air sensor, evaporator temperature or clean switch sensor.When an alarm occurs, the main controller 30 preferably notifies aremotely located central monitoring station 100 via a communication bus102, including LAN/WAN or remote dial-up using, e.g., TCP/IP. Further,the main controller 30 can notify a store manager or refrigerationservice company via a telephone call or page using a modem connected toa telephone line. The alarm and defrost information can be transmittedfrom the main refrigeration controller 30 to the display module 46 fordisplaying the status on the LED display 54.

Referring to FIG. 8, a temperature control logic 70 is shown to controlthe electronic pressure regulator (ESR) 28 for the particular circuit 26being analyzed. In this regard, each electronic pressure regulator 28 iscontrolled by measuring the case temperature with respect to theparticular circuit 26. As shown in FIG. 1, each circuit A, B, C, Dincludes product-simulating probes 50, 50′ that wirelessly transmittemperature data to the analog signal receiver 94. The receiver 94measures the case temperature and transmits the data to therefrigeration controller 30 using the communication network 34. Thetemperature control logic or algorithm 70 is programmed into therefrigeration controller 30.

The temperature control logic 110 may either receive case temperatures(T₁, T₂, T₃, . . . T_(n)) from each case 22 in the particular circuit 26or a single temperature from one case 22 in the circuit 26. Shouldmultiple temperatures be monitored, these temperatures (T₁, T₂, T₃, . .. T_(n)) are manipulated by an average/min/max temperature block 72.Block 72 can either be configured to take the average of each of thetemperatures (T₁, T₂, T₃, . . . T_(n)) received from each of the cases22. Alternatively, the average/min/max temperature block 112 may beconfigured to monitor the minimum and maximum temperatures from thecases 22 to select a mean value to be utilized or some other appropriatevalue. Selection of which option to use will generally be determinedbased upon the type of hardware utilized in the refrigeration controlsystem 10. From block 112, the temperature (T_ct) is applied to an errordetector 114. The error detector 114 compares the desired circuittemperature set point (SP_ct) which is set by the user in therefrigeration controller 30 to the actual measured temperature (T_ct) toprovide an error value (E_ct). Here again, this error value (E_ct) isapplied to a PI/PID/Fuzzy Logic algorithm 108, which is a conventionalrefrigeration control algorithm, to determine a particular percent (%)valve opening (VO_ct) for the particular electronic pressure regulator(ESR) 28 being controlled via the ESR board 42.

While the temperature control logic 110 is efficient to implement,logistically it had inherent disadvantages. For example, each casetemperature measurement sensor required connecting each display case 22to the analog input board 38, which is generally located in thecompressor room 6. This created a lot of wiring and high installationcosts. The invention described herein, however, overcomes thislimitation by wirelessly arranging the transmission of temperature datafrom product simulating probes 50, 50′, or from other temperaturesensors including the discharge temperature sensor 48, defrosttermination sensor 52, return air sensor, evaporator temperature orclean switch sensor, etc. A further improvement to this configuration isto use the display module 46, as shown in circuit A of FIG. 1, as wellas FIG. 7. In this regard, a temperature sensor within each case 22passes the temperature information to the display module 46, whichwirelessly transmits the data to the receiver 94, which sends the datato the controller 30. Under either version, the temperature data istransferred directly from the refrigeration case 22 to the refrigerationcontroller 30 without the need for the analog input board 38, or forwiring the various sensors to the analog input board 38, therebysubstantially reducing wiring and installation costs.

Referring now to FIG. 9, a floating circuit temperature control logic116 is illustrated based upon temperature measurements from theproduct-simulating probe 50, 50′. The floating circuit temperaturecontrol logic 116 begins at start block 118. From start block 118, thecontrol logic proceeds to differential block 120. In differential block120, the average product simulation temperature for the past one-hour orother appropriate time period is subtracted from a maximum allowableproduct temperature to determine a difference (diff). In this regard,measurements from the product probe 50 are preferably taken, forexample, every ten seconds with a running average taken over a certaintime period, such as one hour. The type of product being stored in theparticular refrigeration case 22 generally controls the maximumallowable product temperature. For example, for meat products, a limitof 41° F. is generally the maximum allowable temperature for maintainingmeat in a refrigeration case 22. To provide a further buffer, themaximum allowable product temperature can be set 5° F. lower than thismaximum (i.e., 36° for meat).

From differential block 120, the control logic 116 proceeds todetermination block 122, determination block 124 or determination block126. In determination block 122, if the difference between the averageproduct simulator temperature and the maximum allowable producttemperature from differential block 120 is greater than 5° F., adecrease of the temperature set point for the particular circuit 26 by5° F. is performed at change block 128. From here, the control logicreturns to start block 118. This branch identifies that the averageproduct temperature is too warm, and therefore, needs to be cooled down.At determination block 124, if the difference is greater than −5° F. andless than 5° F., this indicates that the average product temperature issufficiently near the maximum allowable product temperature and nochange of the temperature set point is performed in block 130. Shouldthe difference be less than −5° F. as determined in determination block126, an increase in the temperature set point of the circuit by 5° F. isperformed in block 132.

By floating the circuit temperature for the entire circuit 26 or theparticular case 22 based upon the simulated product temperature, therefrigeration case 22 may be run in a more efficient manner since thecontrol criteria is determined based upon the product temperature andnot the case temperature which is a more accurate indication of desiredtemperatures. It should further be noted that while a differential of 5°F. has been identified in the control logic 116, those skilled in theart would recognize that a higher or a lower temperature differential,may be utilized to provide even further fine tuning and all that isrequired is a high and low temperature differential limit to float thecircuit temperature. It should further be noted that by using thefloating circuit temperature control logic 116 in combination with thefloating suction pressure control logic 80 further energy efficienciescan be realized. Variations of the above apparatus and method aredescribed in U.S. patent application Ser. No. 09/539,563, filed Mar. 31,2000, entitled “Method And Apparatus For Refrigeration System ControlUsing Electronic Evaporator Pressure Regulators,” incorporated herein byreference.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention.

1. A method for refrigeration system control, said method comprising:measuring a simulated product temperature from at least onerefrigeration case in a first refrigeration circuit; wirelesslytransmitting said simulated product temperature to a controller; andelectronically controlling an electronic stepper regulator for saidfirst refrigeration circuit to effect said simulated producttemperature.
 2. The method as defined in claim 1 further comprisingdetermining at least one of a defrost termination temperature, dischargetemperature and a suction pressure.
 3. The method as defined in claim 1further comprising: measuring a second parameter from anotherrefrigeration case in a second refrigeration circuit; wirelesslytransmitting said measured second parameter to said controller; andelectronically controlling a second electronic stepper regulator toeffect said second measured parameter.
 4. The method as defined in claim3 wherein said second parameters is selected from the following group:defrost termination temperature, simulated product temperature, airdischarge temperature, or suction pressure.
 5. The method as defined inclaim 3 wherein said second parameter is suction pressure for acompressor rack.
 6. The method as defined in claim 5 wherein saidcontroller controls said compressor rack capacity based on said measuredsecond parameters.
 7. A method for refrigeration system control, saidmethod comprising: measuring a first parameter from at least onerefrigeration case in a first refrigeration circuit; wirelesslytransmitting said measured first parameter to a controller;electronically controlling an electronic stepper regulator for saidfirst refrigeration circuit to effect said measured first parameter;measuring a second parameter from another refrigeration case in a secondrefrigeration circuit; wirelessly transmitting said measured secondparameter to said controller; and electronically controlling a secondelectronic stepper regulator to effect said second measured parameter;wherein at least one of said first and second parameter is suctionpressure for a compressor rack.
 8. The method as defined in claim 7wherein said controller controls said compressor rack capacity based onsaid measured first and second parameters.
 9. The method as defined inclaim 7 wherein the other of said first and second parameters isselected from the following group: defrost termination temperature,simulated product temperature, discharge temperature, and suctionpressure.